1. Field of the Invention
The present invention relates to an image forming apparatus.
2. Description of the Related Art
In a typical electrophotographic image forming apparatus, a latent image writing unit, such as a laser writing device that optically scans a surface using laser light, writes a latent image on a latent image carrier. The latent image carrier is, for example, a uniformly charged photoreceptor. In an image forming apparatus such as this, depending on a layout within the device, the latent image writing unit becomes an obstruction and results in degradation in the maintainability of the latent image carrier and various peripheral devices. The various peripheral devices include a developing unit or a cleaning unit provided near the latent image carrier.
In Japanese Patent Application Laid-open No. 2849978, an image forming apparatus is described in which a latent image writing unit is fixed to an opening-and-closing cover that can be opened and closed with respect to a fixed cover, and a latent image carrier is fixed to the fixed cover. The fixed cover is a portion of an enclosure of the image forming apparatus. The latent image writing unit is widely separated from a latent image carrier when the opening-and-closing cover is opened. Because the latent image writing unit is retracted from a position opposing the latent image carrier when the opening-and-closing cover is opened, the latent image carrier and peripheral devices thereof are externally exposed, thereby improving maintainability of the latent image carrier and the peripheral devices.
However, sometimes the opening-and-closing cover rattles against the fixed cover resulting in an error in the relative positions of the latent image writing unit and the latent image carrier. Such error leads to degradation in writing position accuracy of the latent image writing unit.
Therefore, the present applicant has proposed an image forming apparatus described in Japanese Patent Application Laid-open No. 2006-157380 (referred to, hereinafter, as “previous application”). In the image forming apparatus described in the previous application, when the opening-and-closing cover is in a closed state, a biasing member biases a reference position component included in a latent image writing unit that is fixed to the opening-and-closing cover. The reference position component comes into contact with a positioning member within the image forming apparatus. As a result, the latent image writing unit can be accurately positioned with respect to a latent image carrier that is fixed to the fixed cover within the image forming apparatus. In other words, decrease in the writing position accuracy of the latent image writing unit can be prevented.
However, when the opening-and-closing cover is closed, the reference position component can collide with the positioning member. Positions of lenses, mirrors, and the like within a casing of the latent image writing unit can shift due to the collision resulting into degraded writing position accuracy of the latent image writing unit.